1. Field of the Invention
The present invention relates to a heat storage dish, and particularly a heat retentive server which is adapted to be heated by electrical induction.
2. Description of Background Information
In environments where food is prepared and cooked in a central location and distributed and served to consumers who are remotely located, such as in hotels, in aircraft and in institutional settings such as hospitals and nursing homes, there is often a delay between the time that the food is prepared, cooked and subsequently placed on a plate or other serving dish, and the time that the food is eventually presented to the consumer for consumption at a remote location, such as a hotel room, hospital room, on aircraft, etc. Accordingly, by the time the food is presented to the consumer, the food can become cold unless special measures are taken to keep the food hot. Various approaches to such meal service problems encountered in such service environments, sometimes referred to as "satelliting" have been employed in the food service and container industries.
One approach to solving such problems associated with the service of meals involves the use of heat retentive servers, serving trays having insulated portions therein, and/or serving containers which retain heat. Such containers typically are adapted to receive a plate containing portions of a meal which are to be kept hot. Such servers typically include an insulated base portion and an insulated dome portion, which together cooperate to define an insulated enclosure which is adapted to receive a plate having such heated meal portions thereon, and maintain the plate and the meal portions in an insulated environment. In some instances, the heat retentive server can include a portion which acts as a heat storage "battery", or a heat sink.
One such heat retentive server is disclosed in U.S. Pat. No. 4,982,722, issued Jan. 8, 1991 to WYATT, and assigned to Aladdin Synergetics, Inc., of Nashville, Tenn. The entirety of this patent is hereby incorporated by reference, as though set forth in full herein.
Such heat retentive servers can be designed to support dishware, which in turn holds a portion of a meal which is to be kept hot. In such circumstances, such a base is commonly called a "pellet" base, and the entire system, i.e., the base, dome and plate, is referred to as a "pellet system". When a heat sink is incorporated into a server base and the base supports a food-carrying dish, such as a plate, the base can be referred to as a plate warmer.
The heat sinks in such systems can include, e.g., a phase-change core, such as that disclosed in U.S. Pat. No. 4,982,722, incorporated by reference above. In other approaches, a solid heat sink can be employed.
In general, heat retentive servers employ convection or conduction heating in order to either heat a food service dish or heat a heat storage battery during food service operations.
U.S. Pat. No. 3,916,872 to KREIS et al., issued Nov. 4, 1975, discloses a heat storage dish comprising a central heat storage disk and an insulating member which surrounds the heat storage dish. The heat storage dish consists of a substantially circular metallic body member which may be equipped with a central opening. The heat storage dish may, in one embodiment, be heated by subjecting it to a high frequency field, thus inductively heating the heat storage dish. U.S. Pat. No. 3,557,774, issued Jan. 26, 1971 to KREIS discloses a heat storage dish having a heat storage plate enclosed between an interior wall and an exterior wall, secured at their edges to prevent the entry of any external substance.
U.S. Pat. No. 4,776,386 to MEIER, issued Oct. 11, 1988, discloses an apparatus for cooling, storing and reheating food using induction heating. This system includes a tray distribution system wherein a tray, which may be adapted to support, e.g., a soup tureen, a dish for meat, a hot beverage cup, a salad plate, and/or a similar plate such as a fruit dish, as well as a trough for cutlery, may be provided. A meal, supported on such a tray can be stored in a refrigerated environment. In this system, the refrigerated cabinet in which the trays are stored includes induction coils. In practice, prior to serving, the cooling system of the refrigerator is turned off and the induction coils are activated to supply heat to the appropriate areas in the tray. U.S. Pat. No. 4,881,590 to MEIER, issued Nov. 21, 1989, discloses a similar system.
U.S. Pat. No. 4,020,310 to SOUDER, Jr. et al., issued Apr. 26, 1977, and U.S. Pat. No. 4,110,587 to SOUDER, Jr. et al., issued Aug. 29, 1978, discloses containers which are specifically designed for induction heating.
U.S. Pat. No. 3,734,077 to MURDOUGH et al., issued May 22, 1973, discloses a server which includes a recess in order to receive a plate. The server comprises an upper shell, a lower shell, a heating pellet and a resilient pad. The pad occupies the space between the under surface of the pellet and the lower shell and performs an insulating function, in addition to directing heat from the pellet in an upward direction rather than downwardly or laterally.
Each of the forgoing systems suffers from disadvantages. For example, systems which employ convection or conduction heating to preheat a food service container prior to employing the food service container to support, e.g., a dish having a food portion which is to be kept hot, require long "lead times" prior to being capable of being effectively used. Thus, such systems require relatively long periods of time in order to preheat the convection systems or other ovens used with said systems and in order to store enough heat in a heat sink or other heat storage means before the container can be usefully employed to keep foods warm in food service environments. Such lead times are undesirable and are typically on the order of about 60 to about 90 minutes and sometimes even longer, prior to the start of delivery or serving of the food to individual consumers.
Such food service containers including heat retentive servers and the like, suffer from other disadvantages. For example, heat retentive servers possess the disadvantage that the entire server can become hot and difficult to handle safely.
Additional disadvantages include the fact that heat retentive servers which act as a heat sink, e.g., which employ a heat storage mass, tend to liberate heat in all directions. However, it is preferable to direct the heat which is liberated from the heat storage mass such that the heat is liberated substantially only within the heat retentive server itself, i.e., that portion of the heat retentive server which is enclosed by the bottom portion, side walls and dome or lid of the server. To achieve such an object, it is preferable to direct the heat given up by the heat storage mass such that the heat is directed upwardly.
The foregoing approaches have failed to provide a heat retentive server wherein the outer portion, e.g., the outer wall portion, is substantially insulated from the central portion, containing the heat storage mass. Additionally, the foregoing approaches have failed to provide a heat retentive server containing a heat sink or heat storage mass which can be rapidly "charged" with stored heat so that the charging operation can coincide with the food placement operation, negating the need for preheating of the heat retentive server. Moreover, the foregoing approaches have generally failed to provide heat retentive servers which can be rapidly heated and prepared for service as described above, but which also provides relatively safe handling characteristics by virtue of having one or more outer peripheral surfaces which remain cool to the touch, and therefore facilitate safe handling. Thus, the foregoing approaches have failed to provide a heat-on-demand pellet system, capable of sequential heating and food placement and food dish placement, and yet which is safe to handle even under sequential, assembly line type conditions.
The foregoing drawbacks all contribute to reduce efficiency and, in some instances, reduce safety, in mass production food service operations as described above.
Thus, the foregoing approaches have failed to satisfy one or more of these aspects, and there has been a continuing need for improvement.